Gripper head

ABSTRACT

This invention relates to an apparatus for picking up products or group of products with a gripper having gripper blades, more particularly for executing cycles of engaging, picking up and displacing packaging units or groups of packaging units, and subsequently delivering these into packaging boxes, the gripper comprising: a frame, having arranged thereon, two holders on two opposite sides of the frame, each having a gripper blade arranged therein, the two gripper blades, each in the shape of an arc, guide wheels for guiding the gripper blades during the rotation about their respective axes which are situated between the gripper blades, a first drive for moving each of the holders away from or towards each other, a second drive for rotatingly turning outwards or drawing inwards each of the arcuate gripper blades, and a third drive for displacing the frame in picking up, displacing and delivering the products, wherein for each gripper blade at least a part of one guide wheel is designed as a pinion with teeth that engage in a row of holes designed as a rack and arranged along the arc circumferential direction of such a gripper blade. In an advantageous exemplary embodiment, the movements of the holders are coupled with a toothed belt via toothed-belt wheels. This construction enables a product or group of products to be picked up, displaced and delivered in a highly controlled manner.

The present invention relates to an apparatus according to the preamble of claim 1.

Such an apparatus is known from EP666149. More particularly, it is described in that publication how two arcuate gripper plates on each side are passed between three guide wheels to be able to perform a rotating movement. It has been found that this movement is particularly suitable for placing products clamped between these plates or blades, for instance egg boxes with the eggs grouped in, for instance, patterns with a 2×5, 2×6, or 2×2×3 arrangement of the eggs, in matching and close-fitting outer boxes, packaging boxes, cases, or crates, and especially, after placement, after rotating away, that is, rotary drawing-in of the plates or blades, to raise the gripper from such an outer box again without damaging the outer box or leaving the egg box behind in an unwanted manner.

Both in placing the products in the outer box and in retracting just the gripper out of the outer box, the gripper blades will mostly move along the walls of the outer box with friction because the dimensions of products and outer box match closely. Depending on the materials used, or even on the condition thereof, for instance in case of much moisture, the gripper blades, as a result of this friction, may to some extent change in position between the guide wheels, or, differently stated, rack to some extent. This may be disadvantageous in subsequent cycles of picking up and placement, especially because the products may thereby be damaged. In the case of egg boxes from cardboard, this may even mean that egg breakage is to be reckoned with.

To obviate this problem, the apparatus according to the invention is characterized in that for each gripper blade at least a part of one guide wheel is designed as a pinion with teeth that engage in a row of holes designed as a gear rack and arranged along the arc circumferential direction of such a gripper blade.

With the gripper according to the present invention, in a highly suitable manner, the gripper blades on either side of the gripper are rotated to the same extent, allowing the products to be engaged in a well-controlled manner without damaging them.

Further exemplary embodiments have as features

-   that the pinion engages along the outer circumference of such a     gripper blade; -   that the first drive for one holder is coupled with the other holder     through a synchronous coupling; -   that the synchronous coupling comprises a combination of endless     toothed belt with two toothed-belt guide wheels, wherein the first     drive with the housing is arranged on and connected with the frame,     and wherein the drive is connected with one holder and with the     toothed belt, wherein the toothed belt is furthermore connected with     the other holder, and wherein the toothed-belt wheels are connected     with the frame; -   that at least one of the guide wheels along the inner circumference     of such a gripper blade is shaft-shaped, wherein, in engaging,     displacing and delivering the product or the group of products, this     shaft-shaped wheel substantially abuts against the upper side of     such a product; -   that the frame is provided with a stop, perpendicular to the feeding     direction of the product or a group of products and situated on the     downstream side of the frame viewed in the feeding direction,     wherein the products upon being fed are stopped by this stop; -   that the stop is in the form of a plate; -   that the position of the stop in the conveying direction is     adjustable with an adjustment connection; -   that the adjustment connection comprises a screw-slot connection;     and/or -   that in engaging, displacing and delivering products or group of     products while considerable seams or interruptions occur in or     between products, parallel to the gripper blades and situated along     the upper side in the conveying direction, the frame is connected     with engagement strips which, in engaging, are positioned engagingly     in the seams, recesses, or interruptions and, upon delivering, are     removed from the seams or interruptions.

The gripper according to the invention will be described in detail with reference to the following figures,

wherein FIG. 1 schematically shows an exemplary embodiment in isometric view,

wherein FIG. 2 represents in isometric view a view of the first drive for the exemplary embodiment from FIG. 1, and

wherein FIG. 3, for this exemplary embodiment, shows in isometric view one of the gripper blades, and the guide and drive thereof.

In the different figures, corresponding parts have been given the same reference characters.

In FIG. 1, gripper 1 is mounted on the lower end of a boom or mast 2 which can be moved up and down to pick up and put down loads. More particularly, this gripper 4 comprises a frame 3 which can be rotated with a rotation mechanism 4 by means of a shaft 3 a in the boom 4. In this way, in certain cases, products will be picked up and set down that have been rotated a quarter turn with respect to a previous cycle. The gripper is equipped with a pair of gripper blades 5, each arranged in an associated holder 6, each on a side of the frame 3. The gripper blades are arcuate, as represented by an arc 5 a, and, when being rotated outwards or drawn in, are rotatably passed round by guiding them between sets of, in each case, three guide wheels 7 a,b,c, with rotation taking place about axes A as indicated in FIG. 3. It will be clear to those skilled in the art that the curvature is such that the axes A are situated between the blades.

For the movements as mentioned above, several drives are needed to execute a cycle of engaging, clamping, displacing, and delivering. For these movements, several slightly different sequential orders can be chosen. Such choice is generally determined by reasons of efficiency, which are generally a combination of adequate space and required and available time. It will be clear to those skilled in the art that such a cycle is realized in a generally known manner by a control, more particularly by a computer program that executes the signal control.

A first drive 9 is used for moving the holders 6 away from or towards each other. As soon as a product, or a group of products, has been positioned in the correct position under the gripper 4, the gripper 4 will be moved down to the proper height, and the holders 6, after the gripper blades 5 have been rotated outwards, will be moved towards each other until the product, or the group of products, is clamped firmly enough. Similarly, after placement in an outer box, and after complete upward retraction out of the outer box, the holders 6 will be moved away from each other to allow a next cycle to be started.

Further details of this drive are indicated in FIG. 2, where, in this exemplary embodiment, the drive 9 is realized pneumatically, with the drive 9 being connected directly with one holder 6 through a bracket 6L via a coupling piece 9 b. Further, this drive 9 is connected by way of a foot 9 a of a drive housing to the frame 3. To cause the other holder 6 to be moved as well, simultaneously, and, after adjustment, in a centered manner, the bracket 6L is connected via a coupling piece 19 with a toothed belt 21, while on the other side of this toothed belt a second coupling piece 20 is situated which is connected with a second bracket 6R on the other holder 6. As is indicated in FIG. 2, the toothed belt is passed over two toothed-belt wheels 22 a,b whose axles are rotatably connected with the frame. What is achieved with great advantage in this way is that with well-controlled feeding of the products a highly uniform engagement, clamping, displacement, and delivery of these products is obtained. It is noted that according to EP666149, for each holder a separate first drive is used.

Furthermore, it is noted that this first driving construction is connected via one of the ends with an end 10 c of the drive of the gripper blades.

In FIG. 3, it is shown in detail how a second drive 10 is arranged, connected with each gripper blade 5 via an end 10 a with cross shaft 10 b adjacent a corresponding bracket 5 a with shaft holes 5 c in order to cause the gripper blades 5 to follow their rotary movement, viz. outward rotation prior to clamping and engagement, and subsequently, after placement of the product or the group of products, inward retraction. As briefly indicated above, the guidance of the gripper blades 5 is executed by sets of guide wheels 7 a,b,c, generally one set on each side of such a gripper blade 5. For this guidance to proceed as uniformly as possible, of each set, one of the guide wheels is designed as a pinion 17 with teeth 17 a which engage in a corresponding row 8 of holes 8 a provided in the circumferential direction of such an arcuate blade 5 a. The pinion 7 and the row 8 function in a generally known manner as a pinion and rack. Advantageously, the sets will be situated on a same continuous shaft, while the set, and hence the shaft, on the inner circumference, substantially abuts against a product, and with this feature too provides for further clamping, for instance of a cover part of such a product.

As already elucidated above, racking upon possible friction and jamming is thus prevented, in particular in the case where a combination as shown is provided on both sides, or also in the case where a long shaft piece with corresponding hole slots is used. In the exemplary embodiment shown, the pinion principle is used for one of the guide wheels 7 a,b,c along the outer circumference of such a gripper blade 5. To those skilled in the art, it will be clear that a similar action is obtained with combinations of several gear wheels.

A third drive (not represented in the figures) is used to displace the gripper 1 as a whole, generally performing a reciprocating vertical movement, for instance by coupling the beam or mast 2 in a generally known manner to such a third drive.

Furthermore, it is indicated in FIG. 1 how products when being fed in conveying direction T can be advanced as far as a stop 30 which is connected with the frame 3 through screw-slot connections 31. As will be clear to those skilled in the art, for this purpose, suitable forms, for instance a plate, will be used. 

1. An apparatus for picking up products or group of products with a gripper having gripper blades, more particularly for executing cycles of engaging, picking up and displacing packaging units or groups of packaging units, and subsequently delivering these into packaging boxes, the gripper comprising: a frame, having arranged thereon, two holders on two opposite sides of the frame, each having a gripper blade arranged therein, said two gripper blades, each in the shape of an arc, guide wheels for guiding the gripper blades during the rotation about their respective axes which are situated between the gripper blades, a first drive for moving each of said holders away from or towards each other, a second drive for rotatingly turning outwards or drawing inwards each of the arcuate gripper blades, and a third drive for displacing the frame in picking up, displacing and delivering the products, characterized in that for each gripper blade at least a part of one guide wheel is designed as a pinion with teeth that engage in a row of holes designed as a rack and arranged along the arc circumferential direction of such a gripper blade.
 2. An apparatus according to claim 1, characterized in that the pinion engages along the outer circumference of such a gripper blade.
 3. An apparatus according to claim 2, characterized in that the first drive for one holder is coupled with the other holder through a synchronous coupling.
 4. An apparatus according to claim 3, characterized in that the synchronous coupling comprises a combination of endless toothed belt with two toothed-belt guide wheels, wherein the first drive with the housing is arranged on and connected with the frame, and wherein the drive is connected with one holder and with the toothed belt, wherein the toothed belt is further connected with the other holder, and wherein the toothed-belt wheels are connected with the frame.
 5. An apparatus according to claim 1, characterized in that at least one of the guide wheels along the inner circumference of such a gripper blade is shaft-shaped, wherein, in engaging, displacing and delivering the product or the group of products, this shaft-shaped wheel abuts substantially against the upper side of such a product.
 6. An apparatus according to any claim 1, characterized in that the frame is provided with a stop, perpendicular to the feeding direction of the product or a group of products and situated on the downstream side of the frame, viewed in the feeding direction, wherein the products upon being fed are stopped by this stop.
 7. An apparatus according to claim 6, characterized in that the stop is in the form of a plate.
 8. An apparatus according to claim 6, characterized in that the position of the stop in the conveying direction is adjustable with an adjustment connection.
 9. An apparatus according to claim 8, characterized in that the adjustment connection comprises a screw-slot connection.
 10. An apparatus according to claim 1, characterized in that in engaging, displacing and delivering products or group of products while considerable seams or interruptions occur in or between products, parallel to the gripper blades and situated along the upper side in the conveying direction, said frame is connected with engagement strips which, in engaging, are positioned engagingly in the seams, recesses, or interruptions and, upon delivering, are removed from the seams or interruptions. 